Isolation Stress Exposure and Consumption of Palatable Diet During the Prepubertal Period Leads to Cellular Changes in the Hippocampus

Social isolation is one of the most potent stressors in the prepubertal period and may influence disease susceptibility or resilience in adulthood. The glucocorticoid response and, consequently, the adaptive response to stress involve important changes in mitochondrial functions and apoptotic signaling. Previous studies have shown that consumption of a palatable diet reduces some stress effects. Therefore, the aim of the present study was to investigate whether isolation stress in early life can lead to cellular alterations in the hippocampus. For this, we evaluated oxidative stress parameters, DNA breakage index, mitochondrial mass and potential, respiratory chain enzyme activities, apoptosis, and necrosis in the hippocampus of juvenile male rats submitted or not to isolation stress during the pre-puberty period. We also verified whether consumption of a palatable diet during this period can modify stress effects. Results show that stress led to an oxidative imbalance, DNA breaks, increased the mitochondrial potential and early apoptosis, and decreased the number of live and necrotic cells. In addition, the palatable diet increased glutathione peroxidase activity, high mitochondrial potential and complex I–III activity in the hippocampus of juvenile rats. The administration of a palatable diet during the isolation period prevented the stress effects that caused the reduction in live cells and increased apoptosis. In conclusion, the stress experienced during the pre-pubertal period induced a hippocampal oxidative imbalance, DNA damage, mitochondrial dysfunction, and increased apoptosis, while consumption of a palatable diet attenuated some of these effects of exposure, such as the reduction in live cells and increased apoptosis, besides favoring an increase in antioxidant enzymes activities.     

Cadmium-induced changes in antioxidant enzymes from the marine alga Nannochloropsis oculata

Cadmium-induced oxidative stress symptoms such as lipid peroxidation and H₂O₂ production were examined in the marine alga Nannochloropsis oculata. Changes in antioxidant enzyme levels and isozyme patterns were also examined. Increasing concentrations of Cd produced growth inhibition. Among the responses to added Cd, the H₂O₂ content and malonyldialdehyde accumulation increased significantly, indicating a state of oxidative stress. In the case of ascorbate peroxidase activity the increase was about 2.5 times and a marked induction of the isozyme APX2 contributed to this increase. Guaiacol peroxidase activity increased about 4-fold, this being due mainly to the isozyme GPX3. Catalase activity increased slightly, whereas superoxide dismutase and glutathione reductase activity decreased markedly. Alterations of antioxidant enzyme levels and isozyme pattern changes in Cd-treated alga suggest that they might be involved in the heavy metal tolerance in this alga.     

Hypobaric hypoxia induces oxidative stress in rat brain

High altitude exposure results in decreased partial pressure of oxygen and an increased formation of reactive oxygen and nitrogen species (RONS), which causes oxidative damage to lipids, proteins and DNA. Exposure to high altitude appears to decrease the activity and effectiveness of antioxidant enzyme system. The antioxidant system is very less in brain tissue and is very much susceptible to hypoxic stress. The aim of the present study was to investigate the time dependent and region specific changes in cortex, hippocampus and striatum on oxidative stress markers on chronic exposure to hypobaric hypoxia. The rats were exposed to simulated high altitude equivalent to 6100 m in animal decompression chamber for 3 and 7 days. Results indicate an increase in oxidative stress as seen by increase in free radical production, nitric oxide level, lipid peroxidation and lactate dehydrogenase levels. The magnitude of increase in oxidative stress was more in 7 days exposure group as compared to 3 days exposure group. The antioxidant defence system such as reduced glutathione (GSH), glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD) and reduced/oxidized glutathione (GSH/GSSG) levels were significantly decreased in all the three regions. The observation suggests that the hippocampus is more susceptible to hypoxia than the cortex and striatum. It may be concluded that hypoxia differentially affects the antioxidant status in the cortex, hippocampus and striatum.     

Weak antioxidant defenses make the heart a target for damage in copper-deficient rats

Copper deficiency causes more salient pathologic changes in the heart than in the liver of rats. Although oxidative stress has been implicated in copper deficiency-induced pathogenesis, little is known about the selective toxicity to the heart. Therefore, we examined the relationship between the severity of copper deficiency-induced oxidative damage and the capacity of antioxidant defense in heart and liver to investigate a possible mechanism for the selective cardiotoxicity. Weanling rats were fed a purified diet deficient in copper (0.4 μg/g diet) or one containing adequate copper (6.0 μg/g diet) for 4 weeks. Copper deficiency induced a 2-fold increase in lipid peroxidation in the heart (thiobarbituric assay) but did not alter peroxidation in the liver. The antioxidant enzymatic activities of superoxide dismutase, catalase, and glutathione peroxidase were, respectively, 3-, 50- and 1.5-fold lower in the heart than in the liver, although these enzymatic activities were depressed in both organs by copper deficiency. In addition, the activity of glutathione reductase was 4 times lower in the heart than in the liver. The data suggest that a weak antioxidant defense system in the heart is responsible for the relatively high degree of oxidative damage in copper-deficient hearts.     

Increased Oxidative Parameters and Decreased Cytokine Levels in an Animal Model of Attention-Deficit/Hyperactivity Disorder

Attention-deficit/hyperactivity disorder (ADHD) is a highly heterogeneous disorder characterized by impairing levels of hyperactivity, impulsivity and inattention. Oxidative and inflammatory parameters have been recognized among its multiple predisposing pathways, and clinical studies indicate that ADHD patients have increased oxidative stress. In this study, we aimed to evaluate oxidative (DCFH oxidation, glutathione levels, glutathione peroxidase, catalase and superoxide dismutase activities) and inflammatory (TNF-α, IL-1β and IL-10) parameters in the most widely accepted animal model of ADHD, the spontaneously hypertensive rats (SHR). Prefrontal cortex, cortex (remaining regions), striatum and hippocampus of adult male SHR and Wistar Kyoto rats were studied. SHR presented increased reactive oxygen species (ROS) production in the cortex, striatum and hippocampus. In SHR, glutathione peroxidase activity was decreased in the prefrontal cortex and hippocampus. TNF-α levels were reduced in the prefrontal cortex, cortex (remaining regions), hippocampus and striatum of SHR. Besides, IL-1β and IL-10 levels were decreased in the cortex of the ADHD model. Results indicate that SHR presented an oxidative profile that is characterized by an increase in ROS production without an effective antioxidant counterbalance. In addition, this strain showed a decrease in cytokine levels, mainly TNF-α, indicating a basal deficit. These results may present a new approach to the cognitive disturbances seen in the SHR.     

Effect of quercetin on daunorubicin-induced heart mitochondria changes in rats

Cancer therapy with daunorubicin is limited by its cardiotoxicity. It has been suggested that daunorubicin-induced free radical generation can be involved. The precise molecular mechanism of daunorubicin-induced cardiotoxicity is still not well understood but it is believed that mitochondria play an important role in this process. It has been reported that flavonoids with antioxidant properties may prevent anthracycline-induced cardiotoxicity. In this work, we investigated the effects of daunorubicin and quercetin on mitochondrial enzyme activities such as ATPase, glutathione peroxidase (GPx) and glutathione reductase (GR). Moreover, we also studied the changes of outer mitochondrial membrane using synchronous fluorescence spectra. The activity of ATPase and GR were significantly increased after daunorubicin application. Pretreatment with quercetin significantly alleviated this increase. On the other hand, GPx activity was significantly decreased and quercetin prevented this decrease. Treatment with quercetin alone had no significant effect on the enzyme activity studied. Quercetin also completely prevented daunorubicin-induced changes in fluorescence of the outer mitochondrial membrane. In conclusion, our data indicate that quercetin may be useful in mitigating daunorubicin-induced cardiotoxicity.     

Effect of abana an ayurvedic formulation,on lipid peroxidation in experimental myocardial infarction in rats

The present study was conducted to elucidate the antioxidant role of an ayurvedic formulation Abana in isoproterenol induced myocardial infarction in rats. In myocardial necrosis induced by isoproterenol, a significant increase in serum iron content with a significant decrease in plasma iron binding capacity, ceruloplasmin activity and glutathione level were observed. There was also a significant increase in lipid peroxides levels on isoproterenol administration. Activities of antioxidant enzymes like superoxide dismutase, catalase, glutathione peroxidase, glutathione-s-transferase, glutathione reductase were decreased significantly in heart with isoproterenol-induced myocardial necrosis. Abana, produced a marked reversal of these metabolic changes related to myocardial infarction induced by isoproterenol. In conclusion ayurvedic formulation Abana exerts its effect by modulating lipid peroxidation and enhancing antioxidant and detoxifying enzyme systems.     

Different effects of exercise tests on the antioxidant enzyme activities in lymphocytes and neutrophils

We have determined the effects of maximal and submaximal cycloergometer tests on the antioxidant enzyme defences of neutrophils and lymphocytes. We also compared the neutrophil and lymphocyte basal enzyme antioxidant activities. A total of 17 well-trained amateur athletes, runners, and cyclists participated in this study. Two tests were performed on an electromagnetic reduction cycloergometer: the maximal exercise test, and the submaximal prolonged exercise test. Blood samples were taken before and after the tests. Basal enzyme activity of superoxide dismutase was higher in lymphocytes but neutrophils presented higher activities of catalase and glutathione peroxidase. The maximal test increased the circulating number of lymphocytes and the activities of catalase and glutathione peroxidase. No changes were observed in lymphocyte number or in lymphocyte antioxidant enzyme activities after the submaximal test. The circulating number of neutrophils increased significantly after the submaximal test. Maximal and submaximal tests decreased the activities of neutrophil glutathione dependent antioxidant enzymes (glutathione peroxidase and glutathione reductase), but no changes were observed in catalase or superoxide dismutase activities after either test. Neither the maximal nor submaximal test produced increases in serum activities of lactate dehydrogenase and creatine kinase (CK).     

Alterations in aortic antioxidant components in an experimental model of atherosclerosis: A time-course study

Antioxidant component alterations in the aorta during atherogenesis were examined in atherosclerosis-susceptible (SUS) Japanese quail fed a cholesterol-supplemented (0.5% w/w) diet. Birds fed a non-supplemented diet provided information on the effects of aging on endogenous antioxidants. One hundred adult SUS males were used. Birds were sacrificed after 0, 4, 8 and 12 weeks on the diets and were examined for plaque development and corresponding antioxidant component alterations in aorta and myocardium. With aging, superoxide dismutase (SOD) activity was increased in both tissues, whereas aortic glutathione peroxidase (GPx) activity and myocardial glutathione reductase (GRd) activity decreased. Myocardial ascorbate levels increased with aging, with a reciprocal decrease in myocardial tocopherol levels. Following 4 weeks of cholesterol supplementation, aortic GRd decreased, SOD activity increased, but activities of GPx and catalase were unchanged. This same qualitative pattern of antioxidant enzyme changes was also found in myocardium. Thus, although aortic antioxidant enzyme changes produced by cholesterol feeding and aging showed some similarities, the early phase of atherogenesis does not simply reflect accelerated aging. In the late stages of atherogenesis, SOD activity returned to baseline, but other antioxidant enzymes remained unaltered from levels characterizing the early phase of lesion development. There was no detectable functional coupling between changes in GPx and GRd, nor between SOD (which produces hydrogen peroxide) and GPx or catalase (which utilize hydrogen peroxide as substrate). Previously reported alterations in erythrocyte antioxidant enzyme components during atherogenesis in quail were not predictive of changes in the corresponding enzymes in the aorta and myocardium.     

Liver Lipid Composition and Antioxidant Enzyme Activities of Spontaneously Hypertensive Rats After Ingestion of Dietary Fats (Fish, Olive and High-Oleic Sunflower Oils)

Hypertension is associated with greater than normal lipoperoxidation and an imbalance in antioxidant status, suggesting that oxidative stress is important in the pathogenesis of this disease. Although many studies have examined the effect of antioxidants in the diet on hypertensión and other disorders, less attention has been given to the evaluation of the role of specific dietary lipids in modulating endogenous antioxidant enzyme status. Previously, we have described that liver antioxidant enzyme activities may be modulated by consumption of different oils in normotensive rats. The purpose of the present study was to examine the effects of feeding different lipidic diets (olive oil, OO, high-oleic-acid sunflower oil, HOSO, and fish oil, FO) on liver antioxidant enzyme activities of spontaneously hypertensive rats (SHR). Plasma and liver lipid composition was also studied. Total triacylglycerol concentration increases in plasma and liver of animals fed on the HOSO and OO diets and decreases in those fed on the FO diet, relative to rats fed the control diet. The animals fed on the oil-enriched diet show similar hepatic cholesterol and phospholipid contents, which are higher than the control group. Consumption of the FO diet results in a decrease in the total cholesterol and phospholipid concentration in plasma, compared with the high-oleic-acid diets. In liver, the FO group show higher levels of polyunsaturated fatty acids (PUFA) of the (n-3) series, in relation to the animals fed on the diets enriched in oleic acid. Livers of FO-fed rats, compared with those of OO- and HOSO-fed rats showed: (i) significantly higher activities of catalase, glutathione peroxidase and Cu/Zn superoxide dismutase; (ii) no differences in the NADPH-cytochrome c reductase activity. The HOSO diet had a similar effect on liver antioxidant enzyme activities as the OO diet. In conclusion, it appears that changes in the liver fatty acid composition due mainly to n-3 lipids may enhance the efficiency of the antioxidant defence system and may yield a benefit in the hypertension status. The two monounsaturated fatty acids oils studied (OO and HOSO), with the same high content of oleic acid, but different content of natural antioxidants, had similar effects on the antioxidant enzyme activities studied.     

Effect of 4-week feeding of deoxynivalenol- or T-2-toxin-contaminated diet on lipid peroxidation and glutathione redox system in the hepatopancreas of common carp (<Emphasis Type="Italic">Cyprinus carpio</Emphasis> L.)

The purpose of study was to investigate the effects of T-2 toxin (4.11 mg T-2 toxin and 0.45 mg HT-2 toxin kg^?1 feed) and deoxynivalenol (5.96 and 0.33 mg 15-acetyl deoxynivalenol (DON)?kg^?1 feed) in 1-year-old common carp juveniles in a 4-week feeding trial. The exposure of mycotoxins resulted in increased mortality in both groups consuming mycotoxin-contaminated diet. Parameters of lipid peroxidation were not affected during the trial, and antioxidant defence also did not show response to oxidative stress; however, glutatione peroxidase activity slightly, but significantly, decreased in the T-2 toxin group. Glutathione S-transferase activity showed moderate decrease as effect of T-2 toxin, which suggests its effect on xenobiotic transformation. Reduced glutathione concentration showed moderate changes as effect of DON exposure, but T-2 toxin has no effect. Expression of phospholipid hydroperoxide glutathione peroxidase (GPx4) genes showed different response to mycotoxin exposure. T-2 toxin caused dual response in the expression of gpx4a (early and late downregulation and mid-term upregulation), but continuous upregulation was found as effect of deoxynivalenol. Expression of the other gene, gpx4b, was upregulated by both trichothecenes during the whole period. The results suggested that trichothecenes have some effect on free radical formation and antioxidant defence, but the changes depend on the duration of exposure and the dose applied, and in case of glutathione peroxidase, there was no correlation between expression of genes and enzyme activity.     

Expression and regulation of antioxidant enzymes in the developing limb support a function of ROS in interdigital cell death

Vertebrate limb development is a well-studied model of apoptosis; however, little is known about the intracellular molecules involved in activating the cell death machinery. We have shown that high levels of reactive oxygen species (ROS) are present in the interdigital 'necrotic' tissue of mouse autopod, and that antioxidants can reduce cell death. Here, we determined the expression pattern of several antioxidant enzymes in order to establish their role in defining the areas with high ROS levels. We found that the genes encoding the superoxide dismutases and catalase are expressed in autopod, but they are downregulated in the interdigital regions at the time ROS levels increased and cell death was first detected. The possible role of superoxide and/or peroxide in activating cell death is supported by the protective effect of a superoxide dismutase/catalase mimetic. Interestingly, we found that peroxidase activity and glutathione peroxidase-4 gene (Gpx4) expression were restricted to the non-apoptotic tissue (e.g., digits) of the developing autopod. Induction of cell death with retinoic acid caused an increase in ROS and decrease in peroxidase activity. Even more inhibition of glutathione peroxidase activity leads to cell death in the digits, suggesting that a decrease in antioxidant activity, likely due to Gpx4, caused an increase in ROS levels, thus triggering apoptosis.     

The study of activity of blood antioxidant enzymes in HIV infection

The HIV infection is accompanied by activation of lipid peroxidation, oxidative modification of lipoprotein complexes, and a decrease in activity of blood serum antioxidant enzymes (superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx)). A significant increase of glutathione reductase observed under these conditions is considered as the antioxidant defense function. These changes are observed at already stages of this disease (in HIV carriers), however, they were much more pronounced in patients with manifested forms of AIDS.     

Omega-3 supplementation can restore glutathione levels and prevent oxidative damage caused by prenatal ethanol exposure

Prenatal ethanol exposure (PNEE) causes long-lasting deficits in brain structure and function. In this study, we have examined the effect of PNEE on antioxidant capacity and oxidative stress in the adult brain with particular focus on four brain regions known to be affected by ethanol: cerebellum, prefrontal cortex and hippocampus (cornu ammonis and dentate gyrus subregions). We have utilized a liquid diet model of fetal alcohol spectrum disorders that is supplied to pregnant Sprague-Dawley rats throughout gestation. To examine the therapeutic potential of omega-3 fatty acid supplementation, a subset of animals were provided with an omega-3-enriched diet from birth until adulthood to examine whether these fatty acids could ameliorate any deficits in antioxidant capacity that occurred due to PNEE. Our results showed that PNEE caused a long-lasting decrease in glutathione levels in all four brain regions analyzed that was accompanied by an increase in lipid peroxidation, a marker of oxidative damage. These results indicate that PNEE induces long-lasting changes in the antioxidant capacity of the brain, and this can lead to a state of oxidative stress. Postnatal omega-3 supplementation was able to increase glutathione levels and reduce lipid peroxidation in PNEE animals, partially reversing the effects of alcohol exposure, particularly in the dentate gyrus and the cerebellum. This is the first study where omega-3 supplementation has been shown to have a beneficial effect in PNEE, reducing oxidative stress and enhancing antioxidant capacity.     

Antioxidant and Antitumor Activities of Selenium- and Zinc-Enriched Oyster Mushroom in Mice

Selenium and zinc are well-known essential trace elements with potent biological functions. However, the possible health benefits of the combined administration of dietary selenium and zinc have not been studied extensively. In this study, we prepared selenium- and zinc-enriched mushrooms (SZMs) containing increased levels of selenium and zinc. The effects of SZMs on antioxidant and antitumor activities were evaluated. Mice were fed with either a control diet or a diet supplemented with SZMs or sodium selenite and zinc sulfate for 6?weeks. Antioxidant capacity was investigated by measuring the activities of antioxidant enzymes and the levels of lipid peroxide products. Results showed that treatment with SZMs significantly increased the activities of glutathione peroxidase (GPx) and superoxide dismutase and decreased the levels of malondialdehyde and lipofuscin. Furthermore, using a mouse model of lung tumors, we found that SZMs significantly decreased the number of tumor nodes with an increase in the activity of GPx. SZMs had a greater effect on the increase in both antioxidant and antitumor activities than did sodium selenite and zinc sulfate. These findings suggest that SZMs may be effective for improving antioxidant capacity and preventing tumors.     

Effects of post-injury hypothermia and nerve growth factor infusion on antioxidant enzyme activity in the rat: implications for clinical therapies

The pathological sequelae of traumatic brain injury (TBI) include increased oxidative stress due to the production of reactive oxygen species (ROS). Regulation of ROS levels following TBI is determined primarily by antioxidant enzyme activity that in turn can be influenced by nerve growth factor (NGF). Hypothermia is one of the current therapies designed to combat the deleterious effects of TBI. However, it has been shown to suppress post-trauma increases in NGF levels in rat brain. The present study sought to determine whether post-injury hypothermia also impairs the antioxidant response to injury, and if such an effect could be reversed by infusion of exogenous NGF. We employed a lateral controlled cortical impact injury model in rat, followed by moderate hypothermia treatment with supplemental intracerebroventricular infusion of NGF or vehicle. The time course of changes in post-injury/intervention levels of NGF and activity of three major enzymes responsible for ROS scavenging, catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD), was determined in the hippocampus. Relative to levels in injured, normothermic animals, hypothermia treatment not only suppressed NGF levels, but also attenuated CAT and GPx activity, and increased SOD activity. Infusion of NGF in injured, hypothermia-treated animals was ineffective in restoring hippocampal antioxidant enzymes activity to levels produced after injury under normothermic conditions, although it was able to increase septal cholinergic (choline acetyltransferase) enzyme activity. These results have implications for clinical treatment of TBI, demonstrating that moderate hypothermia suppresses NGF and the antioxidant response after TBI; the latter cannot be countered by exogenous NGF administration.